The invention relates generally to a process for preparing certain metal phthalocyanine compound and, more particularly to a process for preparing metal phthalocyanine compounds which can be hydrolyzed to form dye developers which are useful in photographic products and processes.
U.S. Pat. No. 3,482,972 discloses a class of metal phthalocyanine dye developers which are useful in photographic processes and products, particularly in diffusion transfer photographic processes and products. Generally, the metal phthalocyanine dye developers are prepared by initially forming the metal phthalocyanine-3,3',3",3'"-tetrasulfonyl halide intermediate, isolating it and then amidating it to form the desired developer. Various specific techniques for carrying out the general reaction scheme are known in the art. U.S. Pat. No. 3,888,876 teaches a process wherein the amidation step is carried out in an aqueous medium. U.S. Pat. No. 3,888,875 discloses a process wherein the amidation step is carried out in a medium which is a mixture of water and a solvent which is a solvent for the amine reactant and the final product but which is not miscible to any significant degree in water. Methylene chloride is disclosed as a preferred solvent.
In the chemical synthesis art there is continuing interest in the discovery of new techniques for the synthesis of known materials. The present application is directed to a novel process for preparing metal phthalocyanine compounds.